甲醛與酚液化柳杉調配比對其所製備Novolak型PF樹脂及成型版性質之影響

Effect of the Blending Ratios of Formaldehyde to Phenol Liquefied ＂Cryptomeria japonica＂ on the Properties of Prepared Novolak PF and Manufactured Moldings

趙中譽(Chung-Yu Chao) ； 張國峻(Kuo-Chun Chang) ； 李文昭(Wen-Jau Lee)

《林產工業》 27卷4期 (2008/12) Pp. 259-269

https://doi.org/10.6561/FPI.2008.27(4).4

摘要

本研究將柳杉（Cryptomeria japonnica D. Don; Japanese cedar）木材以酚為溶劑，硫酸為催化劑進行液化處理，所得液化柳杉與福馬林在甲醛與自由酚之莫耳比（F/P）為0.7/1、0.8/1及0.9/1之條件下合成Novolak型PF樹脂，由試驗結果得知，將酚液化柳杉與福馬林混合時其反應物將發生放熱反應，並形成團塊狀Novolak樹脂，三種合成條件比較，以莫耳比0.8/1者放熱現象最明顯，其反應過程之最高溫度可達82.4℃；GPC分子量分析則顯示甲醛比例較高者，其合成樹脂之分子量較大；DSC熱分析顯示樹脂膠粉添加四氮六甲基圜為硬化劑在加熱過程可發生架橋反應，隨合成時F/P莫耳比提高，其熱硬化所需之Onset溫度及Peak溫度向高溫側偏移，反應熱則降低；將此Novolak樹脂膠粉與木粉、四氮六甲基圜、硬脂酸鋅以重量比60：30：10：1混合，並以160、180及200℃三種溫度熱壓製作成型板，結果得知合成時甲醛比例較高者或熱壓時採用較高溫度者，其成型板經丙酮溶出試驗之重量保留率較高，但內聚強度則以合成時採用F/P莫耳比0.7/1，並以160℃熱壓成型者最佳；由TGA熱分析結果顯示，三種莫耳比比較，以F/P為0.7/1之樹脂為結合劑之成型板有較佳之耐熱性，提高製板時之熱壓溫度可改善其板材之耐熱性。

關鍵字

柳杉 ； 液化木材 ； 成型材 ； Novolak樹脂

並列摘要

The wood of Cryptomeria japonica (Japanese cedar) was liquefied in phenol with H_2SO_4 as a catalyst. The liquefied wood was used to prepare novolak PF resins with the molar ratio of formaldehyde to free phenol that existed in the liquefied wood as 0.7/1, 0.8/1, and 0.9/1. The results showed that an exothermic reaction would occur as blending the liquefied wood with formalin, and they would form a gel-like novolak resin. Comparing among various preparation conditions, blending with the molar ratio of 0.8/1 had the most obvious exothermic phenomenon, its maximum exothermic temperature could reach 82.4 ℃. The GPC analysis showed that the resin prepared with a higher rate of formaldehyde to phenol had a higher molecular weight. The DSC analysis showed that the cross-linking reaction occurred as blending novolak resins with hexamine under heating. Increasing the molar ratio of F/P, the onset and peak temperature for hot-setting shifted to higher temperature, but the reaction heat decreased. The novolak resins were blended with wood powder, hexamine and zinc stearate with a weight ratio of 60:30:10:1, and hot-pressed under 160, 180, and 200℃ to manufacture moldings. The results showed that moldings made with the resin that prepared with a higher rate of formaldehyde to phenol, or hot-pressed with a higher temperature had a higher weight retention percentage after acetone dissolved testing. But the moldings made with novolak resin that prepared with a molar ratio of 0.7/1 and hot-pressed with 160℃ had the best internal bonding strength. Comparing among the three molar ratios, as the results of TGA thermo-analysis, the moldings made with the F/P molar ratio of 0.7/1 had a better heat resistance. Meanwhile, increasing the temperature of hot-pressing could improve the heat resistance of the moldings, too.

並列關鍵字

Cryptomeria japonica ； Liquefied wood ； Moldings ； Novolak resin